Gyarados is a dual Water and Flying type Pokémon. This flying fossil although does not belong to the Dragon type can actually use Dragon type attacks. That is why it is well worth the 400 candies to evolve a Magikarp. However, Gyarados lose Dragon Breath as its fast attack due to the recent 8/20 update.
Here are the strategies and best move set that is super effective on Gyarados.